by Jim Glass
The way NFL football is played has changed over the decades. Statistics in part reflect this, as seen in the steady inflation of passer rating.
But more importantly, what wins games has changed – and this is not reflected in commonly used rating and ranking stats. So even using "inflation adjusted" ratings leads to mistaken conclusions about players of the past when the ratings are based on performance measures that matter the most to us today – but not the ones that mattered most to them.
This article opens with a little rant, then presents the results of multivariate regressions run for the periods 1971-5 and 2006-10 to identify changes in performance measures that matter most to winning.
To illustrate how big these changes have been, it ends by translating Joe Namath's passing numbers – particularly for his 1972 season - into 2010 terms.
MY PET PEEVE, AS A SOON-TO-BE OLD TIMER MYSELF
Pro football fandom is unappreciative of the players of past decades, compared to the fans of other sports.
The 56-game hitting streak of Joe DiMaggio is legendary to baseball fans. But John Unitas' record of throwing TD passes in 47 consecutive games – statistically, a once in 2,000 years achievement! - is unknown to most of my football-fan friends.
"How soon before we stop pretending that Tom Brady isn't the most dominant passing quarterback in the history of the league?, was asked recently a in discussion at Outsiders, reflecting the big part of football fandom that rushes to proclaim the hot player of the moment as the best of all time.
Brady just had his second recent year as #1 passer by AYNA - following seven other seasons with an average rank of 10.4 and a highest of tied 5th-thru-8th, which hardly appears to be the most dominant career in all history. But everyone objecting cited Peyton and other contemporary contenders, not one mentioned a pre-ESPN QB.
One of the reasons for this surely is the immense bias in statistical ratings and rankings in favor of today's players over those of the past which gives the impression that the best players of today are always the best ever.
Zach Sanders last week noted the steady inflation in passer rating. The 1970 league-average of 62.5 would have been 31st in 2010. The NFL Hall of Fame a little while back published an historical passer rating list that ranked Mark Bulger #4 all time. By the NFL's official passer rating formula, the top 17 QBs of all time, and 29 of the top 30, played after 1978.
But Sanders' recommendation of using of inflation-adjusted QB ratings leaves the problem unfixed.
John Unitas was universally considered the dominant QB of his era, voted 5-times First Team All Pro and a 10-time Pro Bowler. Yet a well known football stat site recently proclaimed Bart Starr (one-time All Pro, 4-time Pro Bowler) much the better QB. "We looked at passer rating leaders, and there was Starr ñ not Unitas or Jurgensen or Tittle – atop the leaderboard five times in the 1960s". True, there he is – and as Starr and Unitas were contemporaries, rating inflation is not an issue. But does this mean that the MVP and Pro Bowl voters who actually saw them both play were wrong?
Joe Namath has become the favorite target of revisionists using today's stats to question the HoF status of yesterday's players. SI writer Joe Posnarski in "Reconsidering Namath" describes Namath's numbers as "shockingly bad. You tend to remember Namath as this seminal figure, and of course he was, and then you see those stats and just go: 'Yuck.'".
This has become a popular belief. In a recent discussion at Outsiders comments included: "Namath was a mediocre QB who doesn't belong in the HoF ... if you don't care about interceptions, Namath was wonderful ... he had a very good season in 1967. He got his completion % way up to 52.5%! ... No one thinks Namath's raw numbers match Brady's..." and so on.
Since Namath has become the most denigrated of the HoF old timers, I chose his numbers to convert to 2010 terms.
Were the Hall of Fame voters who saw him play that wrong about Namath? How bad was Namath, really?
OK, that ends the rant. On to the numbers that answer these questions.
Data below for "the 1970s" are for the five years from 1971 through 1975, prior to the big passing rule changes of 1978. Data for "the 2000s" are from 2006 through 2010.
Average points scored per game increased by 2 from the 1970s to the 2000s, from 19.6 to 21.6. That's about 10%, but really not much in light of the scale of some other changes. For instance....
• Defense really did win championships.
The decline in the standard deviation of scoring on both offense and defense reflects both greater "parity" and also a general increase in quality of play. It is seen across-the-board, in many different measures of play. As the average skill and ability of players increases, variance in the level of play from top to bottom diminishes.
The bottom line: Regressing points scored (offense) and allowed (defense) by standard deviation to winning percentage gives these coefficients:'
This is a very significant shift from "defense winning games" to "offense winning games". The defensive coefficient compared to the offensive falls from 18% greater to 24% smaller, a big drop that is bad news for Rex Ryan.
As this is running long, I'll break here.
Part II will look at passing offense statistics, examining what the passing numbers of the past would be today if adjusted by impact on winning percentage – and vice versa.
It will take another look at Unitas vs Starr, and examine just how bad Joe Namath really was.
To be continued....
Tuesday, October 4, 2011
by Jim Glass